Evaluation of Optical Sensors in Predicting Root Yield, Quality and Nitrogen Application in Sugarbeet (Beta vulgaris L.)
Nitrogen management is critical for sugarbeets (Beta vulgaris L.) because it inversely influences root and sucrose yields. From 2015-2017 in Southwestern Ontario this study evaluated the use of optical sensors (SPAD, GreenSeeker) throughout the growing season as a method to guide nitrogen application and harvest date selection by predicting root and sucrose yields. Nitrogen rates (4-5) and cultivars (8-12) were tested in a split block design (3-replications). In all years, few cultivars (≤2) had a root yield response to applied N, which was attributed to high inherent soil fertility. The optimal N rate for sucrose and profits was zero due their negative correlations. Optical sensors correlated negatively with sucrose across the majority (>60%) cultivars tested in September but not at other times. Thus, both sensors are recommended for use in September to predict sucrose yield and to alter harvest date to maximize profits but not to adjust fertilizer N applications.